1. Field of the Invention
The present invention relates to power control devices for flat panel displays and, more specifically, to a system for using future image information to prepare output voltages for flat panel displays.
2. Description of the Related Arts
Light-emitting diodes (LEDs) are being adopted in a wide variety of electronics applications, for example, architectural lighting, automotive head and tail lights, backlights for liquid crystal display devices including personal computer, laptops, high definition TVs, flashlights, etc. Compared to conventional lighting sources such as incandescent lamps and fluorescent lamps, LEDs have significant advantages, including high efficiency, good directionality, color stability, high reliability, long lifetime, small size, and environmental safety.
LEDs are current-driven devices, meaning that the luminous flux (i.e., brightness) generated from them is primarily a function of the current applied through them. Thus regulating the current through the LEDs is an important control technique. To drive a large array of LEDs from a direct current (DC) voltage source, DC-DC switching power converters such as a boost or buck-boost power converters are often used to supply the top rail voltage for several strings of LEDs. In Liquid Crystal Display (LCD) applications using LED backlights, it is often necessary for a controller to control several strings of LEDs in parallel with independent current settings for each string. The controller can then independently control the brightness of different sections of the LCD. Furthermore, the controller can turn different parts of the LCD on or off in a timed manner. In addition the image information is displayed on an LCD panel using separate logic to drive thin film transistor (TFT) LCD panels.
Conventional TFT LCD panels are driven by a timing controller (TCON) bias integrated circuits (IC), power supply, that provide multiple voltages with different current limits for driving the rows and columns of TFT panels. However, these conventional ICs are passive and don't include any intelligence about “future” (next frame) image data and are thus overdesigned to address any sudden change in the current requirements at points of load. Such overdesigning leads to unwanted extra costs.